Magenta poly-azo compounds

ABSTRACT

A compound of Formula (1) and salts thereof: Ar1N=N-J-X-L-X-J-N=NAr2(1) wherein:    &lt;IMAGE&gt;   Ar1 and Ar2 are each independently aryl containing at least two carboxy groups; and L is a group of the Formula (3a) or (3b):     &lt;IMAGE&gt;  (3a)   &lt;IMAGE&gt;  (3b)   in which T1 and T2 each independently is C1-4-alkyl, C1-4-alkoxy or C3-4-alkenyl; T3 and T4 each independently is H, C1-4-alkyl, C1-4-alkoxy or C3-4-alkenyl provided that T3 and T4 are not both H; each X independently is a group of the Formula (4), (5) or (6):    &lt;IMAGE&gt;  (4)   &lt;IMAGE&gt;  (5)   &lt;IMAGE&gt;  (6)  each Z independently is H, halogen, alkyl, NR1R2, SR3 or 0R3; each Y independently is Z, SR4 or OR4; each E independently is Cl or CN; and R1, R2, R3 and R4 are each as defined in the specification. A compound of Formula (1) is suitable for use in the coloration of cellulosic substrates, such as paper, to give bright prints with good light and water fastness. It is especially suitable for use in the printing of paper by non-impact printing techniques, such as ink jet printing, especially thermal ink jet printing.

The specification describes an invention relating to azo compounds whichare useful as the colorants for inks, especially inks used in ink jetprinting.

According to the present invention there is provided a compound ofFormula (1) and salts thereof:

    Ar.sup.1 N═N--J--X--L--X--J--N═NAr.sup.2           ( 1)

wherein: ##STR4## Ar¹ and Ar² are each independently aryl containing atleast two carboxy groups; and

L is a group of the Formula (3a) or (3b): ##STR5## in which T¹ and T²each independently is C₁₋₄ -alkyl, C₁₋₄ -alkoxy or C₃₋₄ -alkenyl; and

T³ and T⁴ each independently is H, C₁₋₄ -alkyl, C₁₋₄ -alkoxy or C₃₋₄-alkenyl provided that T³ and T⁴ are not both H;

each X independently is a group of the Formula (4), (5) or (6): ##STR6##each Z independently is H, halogen, alkyl, NR¹ R², SR³ or OR³ ;

each Y independently is Z, SR⁴ or OR⁴ ;

each E independently is Cl or CN; and

R¹, R², R³ and R⁴ are each independently H, alkyl, substituted alkyl,alkenyl, substituted alkenyl, cycloalkyl, aryl, substituted aryl,aralkyl, substituted aralkyl or R¹ and R² together with the nitrogenatom to which they are attached form a 5 or 6 membered ring;

It is preferred that the dye of Formula (1) has at least as many carboxygroups as sulpho groups.

Each of the groups Ar¹ and Ar² is preferably naphthyl or phenyl,especially phenyl which may carry further substituents in addition tothe two carboxy groups. The additional substituents are preferablyselected from alkyl, especially C₁₋₄ -alkyl; alkoxy, especially C₁₋₄-alkoxy; --SO₃ H; --PO₃ H₂ ; --COSH; --OH; --CO₂ H; halogen, especiallyCl or Br; and optionally substituted C₁₋₄ -alkyl. However, it ispreferred that each of Ar¹ and Ar² carries only two carboxy groups, andis more preferably dicarboxyphenyl, such as 2,4-dicarboxyphenyl,2,3-dicarboxyphenyl, 3,4-dicarboxyphenyl, and especially3,5-dicarboxyphenyl. It is also preferred that Ar¹ and Ar² areidentical.

It is preferred that the chromophores Ar¹ N═N--J--and Ar² N═N--J--areidentical or similar so that they absorb light at approximately the samewavelength.

The variable --SO₃ H group in each J, which may be meta- or para- withrespect to the NH group, is preferably in the meta-position, so that Jis the divalent residue of H-acid.

Examples of the alkyl, alkoxy and alkenyl groups represented by T¹ T²,T³ and T⁴ in the divalent group L are methyl ethyl isopropyl, n-propyl,n-butyl, isobutyl, t-butyl, methoxy, ethoxy, n-propoxy, isopropoxy,n-butoxy, iso-butoxy, t-butoxy and allyl. In the group of Formula (3a),T¹ and T² are preferably identical more preferably C₁₋₄ -alkyl and,especially, each is methyl, so that L is especially2,5-dimethylphen-1,4-ylene-diamino. In the group of Formula (3b), T³ ispreferably H or C₁₋₄ -alkyl, especially methyl and T⁴ is preferably H orC₁₋₄ -alkyl, especially methyl (provided T³ and T⁴ are not both H) and Lis especially 2,5-dimethylpiperazin-1,4-ylene or2-(5-methylpiperazin-1,4-ylene.

When X is of Formula (5) it is preferred that Z is attached to thecarbon atom between the two ring nitrogen atoms and that Y is para to Z.Each X is preferably of Formula (4).

Z is preferably Cl, OR³, SR³ or NR¹ R², especially Cl; OH; SH; alkoxy,such as methoxy or ethoxy; hydroxy--C₂₋₄ -alkylamino, such as mono ordi-(2-hydroxyethyl)amino; morpholinyl; piperidinyl; piperazinyl;4-(hydroxy-C₂₋₄ -alkyl)-piperazin-1-yl, such as4-hydroxyethylpiperazin-1-yl; 4-(C₁₋₄ -alkyl) piperazin-1-yl, such as4-methylpiperazin-1-yl; C₁₋₆ -alkylamino, such as dimethylamino,n-butylamino or n-hexylamino; carboxy-C-₁₋₄ -alkylamino, such as2-carboxymethylamino; arylamino, such as phenylamino, mono-3- ordi-3,5-carboxyanilino; or aralkylamino, such as benzylamino, mono-3- ordi-3,5-carboxyphenylmethylamino. Where Z is alkyl or alkoxy thesepreferably contain from 1 to 4 carbon atoms. Where at least one Z ishalogen, the compound of Formula (1) may be reactive with celluloseunder appropriate temperature and pH conditions. However, this does notappear to contribute to the wet-fastness of the compound when applied toa paper substrate under the normal conditions used in ink jet printingand compounds in which Z is not a cellulose reactive group have beenfound to give equally wet-fast prints on paper to those in which Z is acellulose reactive group.

Each of R¹, R², R³ and R⁴ independently is preferably selected from H,C₁₋₁₀ -alkyl especially C₁₋₄ -alkyl, substituted C₁₋₁₀ -alkyl especiallysubstituted C₁₋₄ -alkyl, phenyl, substituted phenyl, (CH₂)₁₋₄ -phenyland substituted (CH₂)₁₋₄ -phenyl especially benzyl and substitutedbenzyl. When any one of R¹, R², R³ or R⁴ is substituted, the substituentis preferably selected from --OH, --CH₃, --OCH₃, --SO₃ H and --CO₂ H.When R¹ and R² together with the nitrogen radical to which they areattached form a 5- or 6-membered ring, this is preferably morpholine,piperidine or piperazine especially the latter in which the free ringN-atom may be, and preferably is, substituted by a C₁₋₄ -alkyl orhydroxy-C₂₋₄ -alkyl group.

The present invention relates not only to a compound of Formula (1) inthe free acid form, but also to a salt thereof, especially an alkalimetal, ammonium or substituted ammonium salt. Although Formulae (4), (5)and (6) are represented in neutral form, the present invention alsocovers quaternised forms thereof, particularly where the compound ofFormula (1) is in zwitterionic form.

Especially preferred compounds of the present invention are those ofFormula (1) in the form of ammonium, methylammonium or dimethylammoniumsalts in which Ar¹ and Ar² are both 3,5-dicarboxyphenyl; each J is ofFormula (2) in which the sulpho groups are in the 3,6-positions; each Xis of Formula (4) in which Z is Cl, NR¹ R² or OR³ and L is2,5-dimethylphen1,4-ylenediamino, 2-methylpiperazin1,4-ylene or2,5-dimethylpiperazin1,4-ylene. In such a compound of Formula (1) it isespecially preferred that Z is halogen, especially Cl; OH; C₁₋₄ -alkoxy,especially methoxy; hydroxy-C₂₋₄ -alkylamino, especially2-hydroxyethylamino; morpholin-1-yl; piperidin-1-yl, piperazin-1-yl,4-(C₁₋₄ -alkyl)piperazin-1-yl and 4-(hydroxy-C2-4-alkyl)-piperazin-1-yl.

According to a further aspect of the present invention there is provideda process for the preparation of a compound of Formula (1) comprising

(i) diazotisation of amines Ar¹ NH₂ and Ar² NH₂ with a diazotising agentsuch as HNO₂, in the cold and preferably below 5° C. to give thecorresponding diazonium salts;

(ii) condensation of HJH with a compound halo-X-halo, preferablycyanuric chloride, preferably in the presence of base, to give acompound, HJ--X-halo, in which X is as defined above except that Z isCl;

(iii) coupling each of the diazonium salts from (i) above with anequivalent of a compound, HJ--X-halo to give compounds, Ar¹N═N--J--X-halo and Ar² N═N--J--X-halo, in which each X is the same ordifferent to each other and in which each X is as defined above exceptthat Z is Cl;

(iv) the products from (iii) are each condensed with a diamine, H--L--H;

(v) optionally condensing the product from (iv) with a compound, ZH,preferably in the presence of base;

wherein Ar¹, Ar², J, X, L and Z are as defined above unless otherwisestated.

Examples of amines, Ar¹ NH₂ and Ar² NH₂, which may be used in thepreparation of compounds of Formula (1), are, 2-aminoisophthalic acid,4-aminoisophthalic acid, 5-aminoisophthalic acid, 3-aminophthalic acid,4-aminophthalic acid and 2-aminoterephthalic acid.

The divalent group J may be derived from H-acid or K-acid, butpreferably from the former. The two groups represented by J may be thesame or different.

Each group X is preferably derived from cyanuric chloride and the freehalogen atom in the group of formula (4), may be subsequently replacedwith a different group, Z.

A compound of Formula (1) is suitable for use as a colorant especiallyfor cellulosic substrates and gives a good strong magenta shade on paperand related cellulosic substrates, especially those having a surface pHbelow 7, with especially good light- and wet-fastness properties.However some of the present compounds have been found to give printshaving a high water-fastness on substrates with a surface pH of 7 orabove. For example, the dye of Example 5 gives a high wet-fast print onan alkaline paper (Xerox Hammermill 4DP). The brightness of shade, andoften the wet-fastness, of a print on paper of a compound of Formula (1)is significantly better than that given by an equivalent of the compoundof Formula (1) in which the group L is replaced by a differentphen-1,4-ylene-diamino or piperazin-1,4-ylene group not containing analkyl, alkoxy or alkenyl group in one or both of the 2- and 5-positions.

The compounds of Formula (1) are especially useful as colorants in inks,especially aqueous inks, used in ink jet printing and particularlythermal ink jet printing and according to a further feature of thepresent invention there is provided an ink, especially an ink jetprinting ink, comprising a compound of Formula (1) (hereinafter referredto as the colorant) in a liquid medium.

The water fastness of the colorant on paper is increased if it isprinted from an aqueous medium in the form of an ammonium or substitutedammonium salt, especially such a salt derivable from ammonia or avolatile amine. Preferred volatile amines have a vapour pressure of lessthan 60 mm Hg, more preferably less than 20 mm Hg, at 20° C. andatmospheric pressure. Examples of preferred volatile amines includemethylamine, dimethylamine, diethylamine, methylethylamine, propylamineand isopropylamine.

Preferred alkali metal salts are the sodium, potassium and lithiumsalts, and mixtures thereof with NH₄ ⁺ or other substituted ammoniumions derivable from the volatile amines.

The substituted ammonium salt may contain a cation of the formula ⁺ NQ₄in which each Q independently is an organic radical, or two or three Qstogether with the nitrogen atom to which they are attached form aheterocyclic ring and all remaining Qs are selected from C₁₋₄ -alkyl.Preferred organic radicals represented by Q are C₁₋₄ -alkyl radicals,especially methyl radicals. Preferred heterocyclic rings formed by NQ₄are 5- or 6-membered heterocyclic rings.

As examples of substituted ammonium cations of formula ^(+NQ) ₄ theremay be mentioned N⁺ (CH₃)₄, N⁺ (CH₂ CH₃)₄, N-methylpyridinium,N,N-dimethylpiperidinium and N,N-dimethylmorpholinium.

Preferably the substituted ammonium salt contains a cation of theformula ⁺ NHG₃ wherein each G independently is H or C₁₋₄ -alkyl providedat least one G is C₁₋₄ -alkyl, or two or three groups represented by Gtogether with the nitrogen atom to which they are attached form a 5- or6-membered ring, especially a pyridine, piperidine or morpholine ring.It is preferred that the substituted ammonium cation is derived from apreferred volatile amine as hereinbefore defined.

As examples of substituted ammonium cations of formula ⁺ NHG₃ there maybe mentioned (CH ₃)₃ N⁺ H, (CH₃)₂ N⁺ H₂, H₂ N⁺ (CH₃) (CH₂ CH₃), CH₃ N⁺H₃, CH₃ CH₂ N⁺ H₃, H₂ N⁺ (CH₂ CH₃)₂, CH₃ CH₂ CH₂ N⁺ H₃, CH₃ CH₂ CH₂ N⁺H₃, (CH₃)₂ CHN⁺ H₃, isopropylammonium, pyridinium, piperidinium andmorpholinium. Examples of amines used to form such salts includemethylamine, dimethylamine, trimethylamine, ethylamine, n-propylamine,iso-propylamine, n-butylamine, iso-butylamine, sec-butylamine,tert-butylamine, piperidine, pyridine, morpholine, allylamine,diethylamine, triethylamine and mixtures thereof. It is not essentialthat the colorants are completely in the form of the ammonium orsubstituted ammonium salt and mixed alkali metal and either ammonium orsubstituted ammonium salts are effective, especially those in which atleast 50% of the cations are ammonium or substituted ammonium ions.

If the natural pH value of the paper surface is significantly above pH6, this can be adjusted downwards, by the addition to the ink of a saltof an acid with a volatile base, such as ammonia. When the ink dries thebase evaporates to leave the free acid which will lower the pH of thepaper surface in the region of the dye. To minimise damage to the paperit is preferred to use a weak acid, such as acetic acid.

Suitable ink jet printing inks generally contain from 0.5% to 20%preferably from 1% to 10% and especially from 1% to 6% by weight of thecolorant and are generally maintained at a pH from 5 to 9, especiallyfrom 6 to 8 which favours solubility of the colorant in the solventmedium while minimising attack upon the print head or pen.

Suitable liquid media include water alone and mixtures of water withvarious water-soluble or water-miscible organic solvents.

The liquid medium is preferably water or an aqueous medium comprising amixture of water and one or more water-soluble organic solvents,preferably in a weight ratio of water to the solvent(s) from 99:1 to1:99, more preferably from 95:5 to 50:50 and especially from 90:10 to60:40.

The water-soluble organic solvent is preferably a C₁₋₄ -alkanol such asmethanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol,tert-butanol or isobutanol; an amide such as dimethylformamide ordimethylacetamide; an ester such as diacetine; a ketone or ketoalcoholsuch as acetonemethylethylketone, methylisobutyl ketone or diacetonealcohol; an ether such as tetrahydrofuran or dioxane; a polyalkyleneglycol such as polyethylene glycol or polypropylene glycol preferablyhaving molecular weights up to 1000 and especially from 100 to 500 suchas diethylene glycol and triethylene glycol; an alkylene glycolcontaining 2 to 6 carbon atoms such as ethylene glycol, propyleneglycol, butan-1,4-diol, pentan-1,5-diol and hexan-1,6-diol; a polyolsuch as glycerol or 1,2,6-hexanetriol; a lower alkyl ether of apolyhydric alcohol such as 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol,2-(2-ethoxyethoxy)ethanol, 2-[2-(2-methoxyethoxy)ethoxy]ethanol or2-[2-(2-ethoxyethoxy)ethoxy]-ethanol; a heterocyclic ketone such as2-pyrrolidone or N-methylpyrrolidone. In all the above solvents theoxygen atoms may be replaced by sulphur atoms where thio equivalentsexist. The liquid medium preferably contains from 1 to 5 water-solubleorganic solvents, more preferably 1, 2 or 3 such solvents.

Preferred water-soluble organic solvents are selected from lactams,especially 2-pyrrolidone and N-methylpyrrolidone; alkylene glycols orlower alkyl ethers of polyhydric alcohols especially ethylene glycol,diethylene glycol and triethylene glycol and especially2-methoxy-2-ethoxy-2-ethoxyethanol; and polyethylene glycols having amolecular weight of up to 500. A preferred specific solvent mixture is abinary mixture of water and either diethylene glycol, 2-pyrrolidone orN-methylpyrrolidone in a weight ratio as mentioned above.

The ink jet printing ink may also contain one or more of the followingother ingredients

(a) a kogation reducing agent to prevent or inhibit the build up ofresidues (koga) on the resistor surfaces of thermal ink jet printers,and

(b) a buffer, such as sodium borate, to stabilise the pH of the ink.

The kogation-reducing agent is preferably an oxo anion, such asdescribed in EP 425150A. The oxo-anion may be C₂ O₄ ²⁻, SO₃ ²⁻, SO₄ ²⁻,molybdate, AsO₄ ³⁻ or more preferably a phosphate ester, adiorganophosphate or more especially a phosphate salt which isparticularly effective in reducing kogation. As examples of phosphatesalts there may be mentioned dibasic phosphates (HPO₄ ²⁻), monobasicphosphates (H₂ PO⁴⁻) and polyphosphates (P₂ O₇ ⁴⁻). The selection ofcounter ion is not believed to be critical and examples include alkalimetals, ammonium and alkylammonium cations. The kogation-reducing agentis preferably present in the ink at a concentration from 0.001% to 15%,based on oxo-anion, and more preferably from 0.01% to 1% (by weight).

The ink preferably contains less than 5%, more preferably less than 2%,especially less than 1% inorganic salts, e.g. NaCl, KCl and NaNO₃, inorder to enhance solubility of the colorant in the liquid medium andreduce the tendency to deposition of solids in the jets of an ink jetprinter. If the colorant contains significant amounts of inorganic saltsthese may be reduced to a desired level by treating an aqueous solutionor suspension of the colorant with a membrane separation process, suchas reverse osmosis.

An ink containing the colorant as sole colour material is useful as acomponent of a range of 3 or 4 primary printing inks (yellow, magenta,cyan and black) for use in trichromatic printing. However, the ink mayalso contain other coloured materials, especially wet-fast water-solublecoloured materials in addition to the colorant.

The invention also provides a process for ink jet printing a substratewith an ink characterised in that the ink contains a compound of Formula(1) or is as hereinbefore defined. The preferred substrate is a paper.

The invention is illustrated by the following Example in which all partsand percentages are by weight, unless otherwise indicated.

EXAMPLE 1

Preparation of the Compound of Formula (7) ##STR7##

5-Aminoisophthalic acid (9.05g) was stirred in water (500 ml) and the pHadjusted to 8.0 by addition of 2N sodium hydroxide. Sodium nitrite (3.5g) was added and the solution added to a mixture of a little sulphamicacid to give a diazo suspension.

H-Acid (19.5 g, 0.05M) was added to water (500 ml) and the pH adjustedto 6.0 by addition of 2N sodium hydroxide. A solution of cyanuricchloride (10.0 g) in acetone (100 ml) was added to 0°-10° C. Aftermaterial and the filtrate added at 0°-10° C. to the above diazosuspension maintaining the pH at 7.0 by addition of 2N sodium hydroxide.The mixture was stirred for 1 hour at 0°-10° C.

2,5-Dimethylphen1,4-ylene diamine (3.2 g) was dissolved in acetone (100ml) and the solution added to the above mixture. It was stirred for 18hours at 20°-25° C. maintaining the pH at 6.0-7.0 by addition of 2Nsodium hydroxide.

The mixture was heated to 35° C. and salted to 10% with sodium chloride.The product was filtered and washed with 15% sodium chloride solution.

The product was dissolved in water (1l) and heated to 40° C. and slowlyacidified to pH 1 with concentrated hydrochloric acid. The product inthe form of the free acid was filtered and washed with N hydrochloricacid. It was added to water (1l) and the pH adjusted to 9.0 withconcentrated ammonium hydroxide solution. The solution was dialyseduntil chloride ion could no longer be detected, screened through a 0.45μfilter and then evaporated and dried.

The title compound in the form of its ammonium salt was made into a 1%ink in water/diethylene glycol (92.5/7.5) and printed onto plain paperusing a thermal ink jet printer. Bright magenta shades were obtainedhaving high water fastness and good light fastness.

EXAMPLE 2

Preparation of the compound of Formula (8) where R=chloro ##STR8##

5-Aminoisophthalic acid (18.1 g) was added to water (600 ml) and the pHadjusted to 8.0 by addition of 2N sodium hydroxide solution. Sodiumnitrite (7.0 g) was added and the solution added to a mixture ofice/water (100 g) and conc HCl (30 g). The mixture was stirred at 0°-5°C. for 2 hours and excess nitrous acid removed by addition of a littlesulphamic acid.

H-Acid (0.1 mol; 39 g) was added to water (800 ml) and the pH adjustedto 6.0 by addition of 2N sodium hydroxide solution. Cyanuric chloride(20 g) was dissolved in acetone (200 ml) and added to stirred ice/water(200 g). The above H-Acid solution was then added at 0°-10° C. over 5minutes and stirring continued at 0°-10° C. for 2 hours. The solutionwas screened from a trace insoluble material and added to the abovediazo suspension at 0°-10° C. the pH was adjusted to 7.0 by addition of2N sodium hydroxide solution and stirred for 2 hours at 0°-10° C. and pH7.0.

To this solution was added 2,5-dimethylpiperazine (5.5 g) and thetemperature allowed to rise to 25° C. The pH was maintained at 8.5-9.0by addition of 2N sodium hydroxide solution. The mixture was stirred for18 hours at 25° C.

The pH was then adjusted to 7.0 by addition of 2N hydrochloric acid andthe product salted out by addition of sodium chloride. It was filtered,washed with saturated sodium chloride solution and dried at 40° C.

The product was converted into the ammonium salt by dissolving in water(10 g in 500 ml water) and adding to N hydrochloric acid (1l). The freeacid was filtered off redissolved in water (500 ml) by addition ofconcentrated ammonium hydroxide solution and reprecipitated by adding toN hydrochloric acid. After filtering, the product was again dissolved inwater by addition of ammonium hydroxide solution and the solutiondialysed until chloride ions could no longer be detected. The solutionwas screened through a 0.45μ nylon filter to give a clear solution.

An aliquot of this solution was evaporated and dried at 40° C. to givethe title compounds. When this was made into an ink (1%) by dissolvingin water/diethylene glycol (92.5/7.5) and printed onto plain paper usinga thermal ink jet printer, it gave bright magenta shades with high waterfastness.

EXAMPLE 3 Preparation of the compound of Formula (8) where R=hydroxy

The sodium salt of the dye prepared as in Example 2 (10 g) was added to1N sodium hydroxide solution (200 ml) and the solution stirred andheated at 70° C. for 3 hours. Concentrated hydrochloric acid was thenadded until the pH was 7.0 and the product filtered off and washed with10% sodium chloride solution.

This product was dissolved in water and added to 1N hydrochloric acidsolution. The free acid was filtered off, redissolved in water byaddition of concentrated ammonium hydroxide solution to pH 9 and thesolution again added to 1N hydrochloric acid.

After filtering, the product was again dissolved in water by addition ofammonium hydroxide solution and the solution dialysed until no furtherchloride ions could be detected.

The solution was screened through a 0.45μ nylon filter and thenevaporated and dried to give the title compound. When this was made intoan ink (1%) by dissolving in water/diethylene glycol (92.5/7.5) andprinted onto plain paper using a thermal ink jet printer it gave brightmagenta shades with high water fastness.

EXAMPLE 4 Preparation of the compound of Formula (8) whereR=2-hydroxyethylamino

The sodium salt of the dye prepared as in Example 2 (10 g) was added towater (200 ml) and 2-hydroxyethylamine (6.0 g) added. The mixture wasstirred and heated at 75°-80° C. for 6 hours. Concentrated hydrochloricacid was then added until the pH was 3.0 and the mixture cooled to 20°C. The product was filtered off and converted to the ammonium salt as inExample 3 .

When made into an ink (1%) by dissolving in water/diethylene glycol(92.5/7.5) and printed onto plain paper using a thermal ink jet printerit gave bright magenta shades with high water fastness.

EXAMPLE 5 Preparation of the compound of Formula (8) whereR=4-methylpiperazino

In place of the 6.0 g of 2-hydroxyethylamine used in Example 4 there wasused 5 g of 1-methylpiperazine.

The ammonium salt was made into an ink (1%) by dissolving inwater/diethylene glycol (92.5/7.5) and printed onto plain paper using athermal ink jet printer. It gave bright magenta shades having high waterfastness.

EXAMPLE 6 Preparation of the compound of Formula (8) where R=morpholino

In place of 6.0 g of 2-hydroxyethylamine used in Example 4 there wasused 6.0 g of morpholine.

The ammonium salt was made into an ink (1%) by dissolving inwater/diethylene glycol (92.5/7.5) and printed onto plain paper using athermal ink jet printer. It gave bright magenta shades with high waterfastness.

EXAMPLE 7 Preparation of the compound of Formula (8) where R=methoxy

5-Aminoisophthalic acid (18.1 g) was added to water (600 ml) and the pHadjusted to 8.0 by addition of 2N sodium hydroxide solution. Sodiumnitrite (7.0 g) was added and the solution added to a mixture ofice/water (100 g) and concentrated hydrochloric acid (30 g). The mixturewas stirred at 0°-5° C. for 2 hours and excess nitrous acid removed byaddition of a little sulphamic acid.

N-Acetyl-H-acid (0.1M; 50 g) was added to water (500 ml) and thesolution added to the above diazo suspension at 0°-10° C. The pH wasadjusted to 7-8 by addition of 2N sodium hydroxide solution and themixture stirred for 2 hours at 0°-10° C.

To the above mixture was added 47% sodium hydroxide liquor (200 ml) andthe solution heated at 70°-75° C. for 3 hours. The solution wasneutralised to pH 7.0 by addition of concentrated hydrochloric acid andthe mixture cooled to 200° C. Salt, 10% (w/v) was added and the productfiltered off, washed with 15% sodium chloride solution and dried.

This monoazo dye (0.03M; 20.5 g) was dissolved in water (600 ml) byaddition of 2N sodium hydroxide solution to Ph 8.0.2,4-Dichloro-6-methoxy-s-triazine (5.4 g) was dissolved in acetone (50ml) and the solution added to the above monoazo dye solution maintainingthe pH at 6-7 with 2N sodium hydroxide solution and a temperature of25°-30° C. A further 2.5 g of dichloromethoxy-s-triazine was added andstirred further 1 hour at 30° C. The mixture was cooled to 0°-5° C.,screened from a trace of insoluble material and the product precipitatedby addition of acetone. It was filtered off and dried.

9.18 g (0.01M) of this product was dissolved in water and2,5-dimethylpiperazine (0.55 g) added. The mixture was heated at 70° C.maintaining the pH at 8.5-8.7 by addition of 2N sodium hydroxidesolution. After 5 hours the product was salted (20% w/v) and filteredoff.

The ammonium salt was made into an ink (1%) by dissolving inwater/diethylene glycol (92.5/7.5) and printed onto plain paper using athermal ink jet printer. It gave bright magenta shades with high waterfastness.

If the 2,4-dichloro-6-methoxytriazine is replaced by an equivalentamount of 2,4-dichloro-6-ethoxytraizine the dye of Formula (8) in whichR is ClC₂ H₅ is produced. In the form of the ammonium salt this can beused to prepare inks giving prints of similar brightness and waterfastness to the dye in which R is OCH₃.

EXAMPLE 8 Preparation of the compound of Formula (9) where R=hydroxy##STR9## (a) Preparation of the compound of Formula (9) where R=chloro

In place of the 18.1 g of 5-aminophthalic acid used in Example 2 therewas used 18.1 g of 2-aminoterephthalic acid.

(b) The above dyestuff was treated with 1N sodium hydroxide solution asin Example 3 to give (9) where R=hydroxy.

The ammonium salt was prepared as in Example 3. When printed onto plainpaper using a 1% ink (water/diethylene glycol; 92.5/7.5) it gave brightmagenta shades with high water fastness.

EXAMPLE 9 Preparation of the compound of Formula (10) where R=chloro##STR10##

In place of the 5.5 g of 2,5-dimethylpiperazine used in Example 2 therewas used 4.8 g of 2-methylpiperazine. It was converted to the ammoniumsalt as in Example 2 and then made into an ink (1%) by dissolving inwater/diethylene glycol (92.5/7.5). When printed onto plain paper usinga thermal ink jet printer it gave bright magenta shades with good waterfastness.

EXAMPLE 10 Preparation of the compound of Formula (10) where R=hydroxy

The product of Example 9 was treated with 1N sodium hydroxide solutionas in Example 3 to give (10) where R=hydroxy. The ammonium salt wasprepared as in Example 3 and made into an ink (1%) by dissolving inwater/diethylene glycol (92.5/7.5). When printed onto plain paper usinga thermal ink jet printer it gave bright magenta shades with high waterfastness.

EXAMPLE 11 Preparation of the compound of Formula (11) whereR=2-hydroxyethyl amino ##STR11##

The sodium salt of the dye prepared as in Example 1 (10 g) was added towater (200 ml) and 2-hydroxyethylamine (6.0 g) added. The mixture wasstirred and heated at 75°°-80° C. for 6 hours. Concentrated hydrochloricacid was added until the pH was 3.0 and the mixture cooled to 20° C. Theproduct was filtered off and converted to the ammonium salt as inExample 3.

When made into an ink (1%) by dissolving in water/diethylene glycol(92.5/7.5) and printed onto plain paper using a thermal ink jet printerit gave bright magenta shades with good water fastness.

EXAMPLE 12 Preparation of the dye of Formula (11) whereR=3,5-dicarboxyphenyl amino

In place of the 6.0 g of 2-hydroxyethylamine used in Example 11 therewas used 3.0 g of 5-aminoisophthalic acid. It was converted to theammonium salt as in Example 3 and made into an ink (1%) inwater/diethyleneglycol (92.5/7.5). When printed onto plain paper using athermal ink jet printer it gave bright magenta shades with good waterfastness.

Further compounds according to Formula 8 or Formula 11 in which thevalues of R are as set out in the following table may be prepared byreplacing the 2-hydroxyethylamine to that used in Example 4 or Example11 respectively with an equivalent amount of the amine identified in thetable.

    ______________________________________                                        Ex-                                                                           ample Formula  R              Amine                                           ______________________________________                                        13    8        --N(C.sub.2 H.sub.4 OH).sub.2                                                                di(hydroxyethyl)amine                           14    8        --NHC.sub.4 H.sub.9                                                                          butylamine                                      15    8        --N(CH.sub.3).sub.2                                                                          dimethylamine                                   16    8        --NCH.sub.2 Ph benzylamine                                     17    8        4-carboxy PhNH--                                                                             4-carboxyphenylamine                            18    11       piperidinyl    piperidine                                      19    11       4-methylpiperazin-1-yl                                                                       4-methylpiperazine                              20    11       4-tolylamino   4-tolylamine                                    21    11       4-sulphophenylamino                                                                          4-sulphophenylamine                             ______________________________________                                    

We claim:
 1. A compound of Formula (1) or a salts thereof:

    Ar.sup.1 N═N--J--X--L--X--J--N═NAr.sup.2           ( 1)

wherein ##STR12## Ar¹ and Ar² are each independently aryl containing atleast two carboxy groups; and L is a group of the Formula (3b):##STR13## in which T³ and T⁴ each independently is H, C₁₋₄ -alkyl, C₁₋₄-alkoxy or C₃₋₄ -alkenyl provided that T³ and T⁴ are not both H; each Xindependently is a group of the Formula (4), (5) or (6): ##STR14## eachZ independently is H, halogen, alkyl, NR¹ R², SR³ or OR³ ;each Yindependently is Z, SR⁴ or OR⁴ ; each E independently is Cl or CN; andR¹, R², R³ and R⁴ are each independently H, alkyl, substituted alkyl,alkenyl, substituted alkenyl, cycloalkyl, aryl, substituted, aryl,aralkyl or substituted aralkyl, or R¹ and R², together with the nitrogenatom to which they are attached, form a 5 or 6 membered ring.
 2. Acompound according to claim 1 wherein L is of Formula 3(b) and T³ andT.sup. 4 each independently is H, C₁₋₄ -alkyl or C₃₋₄ -alkenyl providedthat T³ and T⁴ are not both H.
 3. A compound according to claim 1 orclaim 2 wherein L is 2,5-dimethylpiperazin-1,4-ylene.
 4. A compoundaccording to any one of claims 1 to 3 wherein J is of Formula (2) inwhich the SO₃ H groups are in the 3,6-positions.
 5. A compound accordingto any one of claims 1 to 4 wherein Ar¹ and Ar² are both3,5-dicarboxyphenyl.
 6. A compound according to any one of claims 1 to 5wherein each X is of the Formula (4) in which Z is H, halogen, C₁₋₄-alkyl, NR¹ R², SR³ or OR³.
 7. A compound according to claim 6 wherein Zis selected from H, OR³, NR¹ R², morpholin-1-yl, piperidin-1-yl,piperazin-1-yl and substituted piperazin-1-yl.
 8. A compound accordingto claim 6 or claim 7 wherein R¹ is H, C₁₋₄ -alkyl, phenyl,carboxyphenyl, dicarboxyphenyl or hydroxy-C₂₋₄ -alkyl, R² is H, C₁₋₄-alkyl or hydroxy C₂₋₄ -alkyl and R³ is H or C₁₋₄ -alkyl.
 9. A compoundaccording to any one of claims 6 to 8 wherein Z is selected from Cl, OH,SH, C₁₋₄ -alkoxy, mono- or di-C₁₋₆ -alkylamino mono- di-(hydroxy-C₂₋₄-alkyl)amino, carboxylalkylamino, phenylamino, 3- or4-carboxyphenylamino, 3,5-, 3,4- or 2,4-dicarboxyphenylamino,benzylamino, morpholin-1-yl, piperidin-1-yl, piperazin-1-yl, 4-C₁₋₄-alkylpiperazin-1-yl, 4(hydroxy-C₂₋₄ -alkyl)piperazin-1-yl.
 10. Thecompound of claim 1 whereinAr¹ and Ar² are both 3,5-dicarboxyphenyl;each J is of Formula (2) in which the sulpho groups are in the3,6-positions; each X is of Formula (4) in which Z is Cl, NR¹ R² or OR³; and L is 2,5-dimethylpiperazin-1,4-ylene;in the form of its ammonium,methylammonium or dimethylammonium salt.
 11. The compound of claim 1whereinAr¹ and Ar² are both 3,5-dicarboxyphenyl; each J is of Formula(2) in which the sulpho groups are in the 3,6-positions; each X is ofFormula (4) in which Z is Cl, NR¹ R² or OR³ ; and L is2-methylpiperazin-1,4-ylene;in the form of its ammonium, methylammoniumor dimethylammonium salt.
 12. A compound according to anyone of claims 1to 12 wherein Z is selected from Cl, --OH, --OCH₃ and --NHCH₂ CH₂ OH.13. A compound according to any one of claims 1 to 12 in the form of anammonium, substituted ammonium or alkali metal salt or a mixture of suchsalts.
 14. An ink comprising a solution of a compound according to claim13 in an aqueous medium.
 15. An ink according to claim 14 wherein theaqueous medium comprises a mixture of water and one or morewater-miscible organic solvents in the ratio 95:5 to 50:50.
 16. An inkaccording to claim 14 or claim 15 containing from 1% to 6% by weight ofsaid compound.